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PDF: The Cure for Dawdling Digital Files

(December 1999) posted on Tue Dec 14, 1999

Learn the basics of creating PDF files.


By Mark A. Coudray

click an image below to view slideshow

The transmission situation is made even worse by the huge size of files today, especially large-format graphics, which can range from 450 MB to well over 1 GB in size. While fractal compression is becoming a viable means of lossless compression (where compression is based on commonality of color or other graphic attributes), we still face the hindrance of using courier and overnight delivery services to move the files on traditional magnetic or optical media. (For more about lossy and lossless compression, see my Prepress Wire column, "File Compression for Graphic Images," in the Sept. '98 issue of Screen Printing magazine, page 116.)

 

As if all of this were not enough, we battle the perpetual problem of platform incompatibility--Mac vs. PC vs. UNIX workstation vs. proprietary system. Even though noise about incompatibility has died down somewhat in the last year or so, it still remains an issue and can seriously interfere with digital throughput in prepress.

 

It is precisely for these reasons that the Adobe PDF workflow is beginning to take shape.

 

PDF to the rescue

PDF, which stands for portable document format, is a platform-independent graphic file format that accommodates good compression levels and allows us to move graphic files across platforms, networks, and the Internet without fear of compromising image integrity. With PDF, all the font issues mentioned previously vanish. The positions of imbedded images and other graphic elements are stable and maintained throughout the imaging process. In simple terms, what we see on the computer screen will reproduce exactly as it appears--with no surprises.

 

Creating PDF Graphics Files

1. Generate a graphic file as you would any electronic file for screen printing or your particular digital-color output device. Compose and preflight the graphic, making sure the file incorporates all elements of the image (including screen and outline fonts).

 

2. Set up Adobe Acrobat Distiller job options based on your compression preferences, output resolution, color space, etc. Do not convert native colors to RGB. File compatibility should be set to "binary" to minimize PDF file size.

 

3. Select the appropriate printer driver and PPD (the correct settings for your particular system are listed on Adobe's Website at www.adobe.com).

 

4. Determine whether you want the image in preseparated or composite format when converted to PDF.

 

5. Verify document size, fonts, spot colors (if any), trapping information, and OPI comments.


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